Based on factors such as whether key stars are still on board, how long it has been since the last film and how that performed, the researchers say they can calculate what producers can expect to gross relative to a film in the same genre that is not a sequel…

The research, which will be published in the Journal of Marketing this month, examined data from all 101 movie sequels released in North American theatres between 1998 and 2006 and a matched subsample of stand-alone films with similar characteristics. According to the formula, upcoming sequel The Twilight Saga: New Moon should be expected to return $34m more for the producers in its US run than a comparable vampire/ teen romance movie with the same characteristics that is not a sequel.